Which of the following chemical entities can act as semipermeable membrane ?

Options

A. `Cu_(2)[Fe(CN)_(6)]`
B. `Cu(SCN_(2)`
C. `BaC_(2)O_(4)`
D. `BaSO_(4)`

Answer

To determine which chemical entity can act as a semi-permeable membrane, we need to analyze the properties of the given options and understand what constitutes a semi-permeable membrane.

### Step-by-Step Solution:

1. **Understanding Semi-Permeable Membranes**:
- A semi-permeable membrane allows certain molecules or ions to pass through while blocking others. This property is crucial for processes like osmosis and diffusion.

2. **Evaluating the Options**:
- We need to examine each of the provided options to see if they can function as a semi-permeable membrane.

3. **Option 1: Copper Ferrocyanide (Cu2[Fe(CN)6])**:
- Copper ferrocyanide is known to form a gelatinous precipitate that can act as a semi-permeable membrane. It allows the passage of certain ions while blocking others, making it suitable for this purpose.

4. **Option 2: Copper Thiocyanide (Cu(SCN)2)**:
- Copper thiocyanide does not exhibit the properties required for a semi-permeable membrane. It does not form a suitable structure for selective permeability.

5. **Option 3: Barium Oxalate (BaC2O4)**:
- Barium oxalate is also not known for its semi-permeable properties. It does not create a membrane that selectively allows the passage of ions or molecules.

6. **Option 4: Barium Sulfate (BaSO4)**:
- Barium sulfate is another compound that does not function as a semi-permeable membrane. It is generally insoluble in water and does not provide the necessary permeability characteristics.

7. **Conclusion**:
- After evaluating all options, we conclude that the only chemical entity that can act as a semi-permeable membrane is **Copper Ferrocyanide (Option 1)**.

### Final Answer:
The chemical entity that can act as a semi-permeable membrane is **Copper Ferrocyanide (Cu2[Fe(CN)6])**.